1. Field of the Invention
The present invention relates to a flash camera with a built-in strobe, and more particularly concerns an automatic exposure controlling camera provided with and operatively connected with the built-in strobe.
2. Prior Art
As a driving means of an aperture control means in a conventional flash camera apparatus comprising an aperture control means using deflection angles of an electric indicator such as an ampere meter, the aperture has been controlled by supplying a photo-current to the indicator. The photo-current responds to an object intensity by using an optoelectro transducer made of silicon and selen. Since it is necessary that the photo-current is large to a certain extent for driving the indicator, a chip area of the optoelectro transducer needs to be large resulting in the problems of high costs and a large installation space. In addition, there was another problem in the optoelectro transducer made of selen which is relatively cheap that the transducer has a poor linearity and is liable to deteriorate.
As another driving means there has been another aperture controlling system where a photo-current responding to an object brightness is supplied to an indicator as described above, but an optoelectro transducer is made of mainly CdS. In that system a transducer operation is largely affected by a voltage variation of a power source and therefore a mercury battery capsule of supplying a stable voltage has been employed as the power source. Accordingly, this system has drawbacks that the device using CdS as the transducer is expensive and that the mercury battery has only a small capacity. When one forgets to turn off a power switch after use, the mercury battery is liable to discharge soon and the mercury battery has to be exchanged.
In order to avoid such trouble, it is devised in the abovementioned driving means that a switch which is for example interlocked with a shutter release button is provided in a loop including the mercury battery and the indicator. By such a configuration electric power is supplied to the indicator only when a photographing is made. But there has been still a problem of an exposure error arising from a response delay of the indicator for the object brightness and/or a damping movement of a pointer of the indicator when the shutter button is pushed down.
Moreover, there are several problems in a brightness check circuit (alarm circuit for insufficient brightness) of the abovementioned flash camera comprising the aperture control means using deflection angles of the indicator. There have been conventionally used, for example, the following two methods. One method is an indication method where an alarm mark is fixed to a part of the aperture control means, for example, to a locking means of the pointer or a stepped gear for the detection of the deflection angles of the indicator, and the alarm for the photographer is made by displaying the alarm mark in the finder. Another method is to lock the shutter release button when the object brightness is not sufficient for a photographing.
However, these two methods have drawbacks. In the former case it is difficult to observe the alarm mark in the finder when the photographer observes it in the dark. While in the latter case the mechanical configuration becomes extremely complex.
In the fundamental operation of the aperture control means of the so far described flash camera, it is further necessary that the deflection angle of the indicator's pointer is controlled by factors other than the object brightness. Such factors are film sensitivity and whether the built-in strobe is used when the photographing needs it. However, in the conventional flash camera the aperture control usually has nothing to do with the deflection angles of the indicator's pointer when the built-in strobe apparatus is used, and the aperture is simply controlled by the object distance. In other words, the so far described conventional flash camera usually comprises two aperture control means. One aperture control means operates responding to the deflection angles of the indicator's pointer, while the other control means is independent from the former and operates responding to other conditions such as object brightness when the built-in strobe is used. Accordingly, the mechanical configuration thereof has been quite complex. This results in several problems in the conventional flash camera, for example, an increase of number of parts, assembly difficulty and difficulty in making the camera body compact.